Once the interaction is established and both players have decided to play C or D, both players receive the same reward \(R\)  (penalty \(P\) ) for mutual cooperation (mutual defection). Unilateral cooperation provides the sucker's payoff \(S\)  for the cooperative player and the temptation to defect \(T\)  for the defecting one. The payoff matrix corresponds to the preferences associated with the PD when the parameters satisfy the ordering, \(T > R > P > S\)  [1]}.
For the sake of a simple representation, we sometimes use the Donor game [1]}, a special case of the PD, with \(T = b,\ R = b-c,\ P = 0,\ S = -c\) , where \(b\)  and \(c\)  stand for the benefit and cost of cooperation, respectively.
